Poly(amidoamine) Dendrimers: An Excellent Intrinsic Flame Retardant and Curing Agent for Epoxy Resins

Considerable efforts have been made to fabricate the intrinsic epoxy resin (EP) with excellent flame retardancy and mechanical properties. However, conventional single molecule flame retardants have met the bottleneck after the massive research studies of the past decade, and with the development of the polymer technology, dendritic flame retardants have been studied due to their versatility and more efficient flame retardancy. Herein, poly-amidoamine (PAMAM) dendrimer flame retardants of different generations were synthesized and utilized as a curing agent and a flame retardant to fabricate the intrinsic EP materials. Their impacts on integrated properties of an EP matrix were studied thoroughly. As expected, the thermal stability, the fire safety, and the flexural capacity of EP/PAMAM thermosets were highly strengthened. The results showed that with 20 wt % loading content of the third-generation PAMAM(G3) dendrimer in the EP matrix (named as EP/20G3), its limited oxygen index value reached up to 26.4% and passed the UL-94 V-0 level. The peak heat release rate and the total heat release data decreased by 51.1 and 60.3%, respectively. Furthermore, the values of T_g, flexural strength, and flexural modulus of EP/20G3 were also promoted comparing with that of the pure EP. At the same time, as an amino-abundant compound, PAMAM dendrimers with different generations can also be served as a curing agent for EP instead of the commonly used diethylenetriamine. It means that PAMAM dendrimers play a dual role in the preparation of flame retardant EP in this system.